(1) Field of the Invention
The present invention has to do with a welding pool support device for energy beam welding, with a metal structure, which on a beam outlet side of a welding seam zone of a workpiece system is put against the beam outlet side and being in contact with it by a number of touching points for stopping any movement of melt out of the welding zone, which is achieved by the energy beam in the workpiece system, by a relative movement of the energy beam and the workpiece system, the former going along the weld seam zone.
(2) The Prior Art
On welding thick workpiece using an energy beam, in particular an electron beam, the melt produced by the energy beam in the welding zone has a tendency to move out of the welding zone, since welding of thick workpieces has to take place at a low speed, that is to say relative movement of the energy beam and the workpiece system. The tendency of the melt to move out of the welding zone is very strong in the case of vertical direction of the energy beam.
For stopping any movement of the melt out of the welding zone the melt has to be supported by an adequate element. This is possible for example by putting a block of material, which is identical with the material of the workpiece system to be welded, against the beam outlet side of the workpiece system. In case of welding with an energy beam coming down in vertical direction it is put against the lower side of the weld seam zone. With energy beam welding, a certain part of the beam always comes out of the backside of the workpiece system and this part then goes into the support material. Thus, the latter is melted and, on re-solidification, is firmly joined to the workpiece system. Separating a solid support body from the workpiece system is difficult and expensive.
It has furthermore been noted that in zones near the beam outlet side of the weld seam there are shortcomings such as hollow spaces, if the support material is tightly touching the beam outlet side; obviously gases which segregate from the welding zone which, are not able to get out, because the weld pool support material comes up close against the weld outlet side, and cause detrimental hollow spaces.
Attempts have been made to overcome these troubles by using a trough as a weld pool support, which has in it wires being oriented in the direction of the weld seam zone so that, for the welding operation the wires are put against the beam outlet side of the workpiece system. Furthermore a stack of sheet metal strips has been used for support of the pool. The strips are placed on edge and are put against the beam outlet side.
Though it is true that these structures for supporting the pool are more easily taken away after welding than a solid supporting body, as seen in the direction of their length they do not make allowance for uneven parts of the workpiece system very well, if the surface of the workpiece system is uneven, so that the pool supporting effect is not made certain, while on the other hand on a smooth beam outlet side or smooth part of it on the two sides of the weld seam zone they frequently have such a tightening effect that gases, segregating from the weld near the beam outlet side, are not able to come out of the material on the beam outlet side, which then causes detrimental hollow spaces.